Water footprint is an indicator of “actual” water consumption that holistically considers the amounts of direct and indirect water consumed in the production of goods and services. It refers to the total amount of clean water consumed and/or polluted by a person, product, sector, basin or country in production processes per unit time. In other words, the water footprint is the most comprehensive indicator that measures our water consumption – that is, the water use and pollution we cause. From this perspective, water footprint is not only the water flowing from the tap, the water taken from the source to the field, or the use of visible water; on the contrary, it is directly and indirectly related to water. It is clearly seen that all internal and external consumption causes water footprint. Water footprint includes not only our direct water consumption, but it also reveals our “invisible water consumption” such as the water consumption in the products we buy, the water footprint we cause in other geographies with imported products, and the footprint we cause on other people’s “fair water right” on a global scale with unnecessary use.
Water footprint is a versatile indicator that shows not only the volume of water, but also the type of water used (green, blue, grey), when and where it is used.
Water footprint is a criterion that assesses both direct water use and indirect water use in the production process.
Direct water footprint refers to the water consumption of a consumer or producer and the pollution value associated with water use.
Indirect water footprint: The indirect water footprint of a consumer or producer corresponds to the water consumption and pollution required for the production of consumed or manufactured products. It equals to the sum of the water footprints of all products consumed by consumers or all (non-water) inputs used by producers.
For example, in meat consumption, the consumer’s direct water footprint refers to the volume of water consumed and polluted when preparing and cooking meat. The indirect water footprint of the meat consumer depends on the direct water footprint of the retailer selling the meat, the food processor preparing the meat for sale, the farm where the animals are raised, and the agricultural farm producing feed for the animals [1].
Components of the Water Footprint
The water footprint has three components: blue, green and grey water footprint, which represent water use and quality.
Blue Water Footprint
The blue water footprint is the total volume of fresh surface and groundwater needed to produce a commodity. Consumption of drinking water, irrigation water and industrial water can be considered as blue water footprint.
Blue water footprint can be defined as the gross water taken into the water transmission network from surface or groundwater resources for irrigated agriculture, industrial and domestic water uses. For example; for irrigated agriculture, evaporation loss can be expressed as the sum of water used by the crop and water drained. Blue water footprint in the industrial and drinking-utility water sectors can be defined as the water supplied to these sectors from the existing surface and groundwater bodies in a basin.
Irrigated Agriculture Blue Water Footprint (volume/time) = Evaporated Blue Water + Blue Water Included in the Product + Amount of Drainage
Green Water Footprint
Green water footprint is the total volume of rainwater needed to produce a commodity. It is especially valid for agricultural, horticultural and forest products.
Green water footprint is water originating from precipitation stored in the soil and consumed by plants through transpiration and evaporation.
- Green water footprint refers to terrestrial precipitation that does not run off and does not mix with groundwater, but that is stored in the soil or remains temporarily above the soil or vegetation.
- It refers to the total amount of rainwater incorporated into the harvested plant by rainwater evapotranspiration that takes place in fields and forest areas.
Green Water Footprint (volume/time) = Green Water Evaporated + Green Water Included in the Product
Grey Water Footprint
Grey water footprint is the amount of fresh water required to assimilate pollutants to meet water quality standards. Grey water footprint can be calculated for point and/or diffuse sources of pollution.
• Grey water footprint refers to pollution. It is defined as the volume of freshwater required to reduce the pollution load to natural background concentrations in the receiving water body.
• The grey water footprint is calculated by dividing the pollution load by the difference between the current water quality status in the environment as a result of pollution and the natural background concentration.
• The most important issue for grey water footprint calculation is the determination of water quality standard and natural background concentration.
Grey Water Footprint (volume/time) = Pollutant Load / (Maximum Measured Concentration in the Receiving Water Body – Natural Concentration in the Receiving Water Body)
WATER FOOTPRINT OF TÜRKİYE
Agricultural Water Footprint
Total water footprint of Türkiye is 140 billion m3/year. 89% of Türkiye’s total water footprint is caused by the agricultural sector, 7% by domestic water use and 4% by industrial production. Green water constitutes more than 66% of the water used in plant production, which is an important part of the agricultural sector. The water footprint of grazing in this sector consists largely of green water. These rates show how important precipitation is for the agricultural sector and that this sector will be inevitably impacted by drought conditions. Approximately 20% of the water used in plant production is blue water. This draws attention to irrigation methods and efficient use of water resources in production [3].
Urban and Industrial Water Footprint
When assessing the water footprint of agriculture, the focus is on blue and green water footprints, whereas in the case of urban and industrial footprint, the grey water footprint is crucial. In Türkiye, grey water footprint is 87% in urban water footprint and 92% in industrial water footprint. The dominance of grey water footprint in industrial and urban water footprint in Türkiye, combined with the economic growth and population growth estimations of the country, makes it possible to say that grey water footprint will pose a risk in terms of water quality in the future [3].
“What lies in the basis of the interest in water footprint is the awareness of the impacts of our consumptions on freshwater resources. Water footprint is an extremely effective tool for addressing production and supply chains as a whole and better understanding problems such as water scarcity and pollution.” (Arjen Y. Hoekstra)
When the total blue water footprint amounts and average agricultural income of these products are assessed using the average agricultural production data between 2013 and 2019, it was determined that 30 agricultural products were ahead of other products in terms of total production, blue water footprint and agricultural income [2]. Among these products, 12 of them (wheat, corn, tomato, alfalfa, grapes, potatoes, cotton, peppers, sugar beet, sunflower, apple, vetch/ervil) are the most important agricultural products of Türkiye in terms of annual production, blue water footprint and agricultural income; especially corn, wheat and alfalfa ranked at the top in all three categories.
REFERENCES
[1] Hoekstra, A.Y., Chapagain, A.K., Aldaya, M.M., Mekonnen, M.M. (2011). The Water Footprint Assessment Manual Setting the Global Standard, Washington/London
[2] Pilevneli, T., Capar, G., Cerda C. S.,. (2023). Investigation of climate change impacts on agricultural production in Turkey using volumetric water footprint approach, Sustainable Production and Consumption. Vol 35 (2023), 605-623. DOI: https://doi.org/10.1016/j.spc.2022.12.013.
[3] Türkiye’nin Su Ayak İzi Raporu. (2014) Su, Üretim ve Uluslararası Ticaret İlişkisi, WWF-Türkiye.